“Ever notice that MKV files load significantly slower than before in VLC on Mac OS X 10.6 (Snow Leopard)? I did, and for someone who has a lot of media files encoded in the format, it’s almost unusable to have to wait a minute while seeing the CPU on one core maxed out. The version of VLC player I have is 1.0.3, the latest as of this post. However, the issue seems to be around since at least 1.0.1 as discussed on this page:http://forum.videolan.org/viewtopic.php?f=12&t=64302&start=15

The fix is pretty simple assuming you are not scared of entering a command in the terminal: